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I'm trying to set up a Active Directory Domain Controller on an Ubuntu 16.04 instance on Amazon's EC2 micro services. I do everything right (following at least three different tutorials) and get all the server side tests to run and go fine. My most recent attempt used this tutorial:https://wiki.samba.org/index.php/Setting_up_Samba_as_an_Active_Directory_Domain_Controller (although I got the kerberos install list from Step 2 of https://www.tecmint.com/install-samba4-active-directory-ubuntu/).

But when I try to connect from Windows 10 (as explained here https://wiki.samba.org/index.php/Windows_DNS_Configuration), I get the following error:

Note: This information is intended for a network administrator. If you are not your network's administrator, notify the administrator that you received this information, which has been recorded in the file C:\Windows\debug\dcdiag.txt.

DNS was successfully queried for the service location (SRV) resource record used to locate a domain controller for domain "ad.company.com.my":

The query was for the SRV record for _ldap._tcp.dc._msdcs.ad.company.com.my

The following domain controllers were identified by the query: dc1.ad.company.com.my

However no domain controllers could be contacted.

Common causes of this error include:

  • Host (A) or (AAAA) records that map the names of the domain controllers to their IP addresses are missing or contain incorrect addresses.

  • Domain controllers registered in DNS are not connected to the network or are not running.

My setup: AWS Micro instance running Ubuntu 16.04 LTS. Elastic IP address set so that I have a static IP address for the server.

The Windows client is a virtual machine. It has the public IP address of the amazon instance set as per instructed on the samba wiki (https://wiki.samba.org/index.php/Windows_DNS_Configuration).

All of these work: host -t A ad.company.com.my host -t A dc1 ping -c3 ad.company.com.my ping -c3 dc1.ad.company.com.my

Configuration files:

/etc/network/interfaces:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# Source interfaces
# Please check /etc/network/interfaces.d before changing this file
# as interfaces may have been defined in /etc/network/interfaces.d
# See LP: #1262951
# source /etc/network/interfaces.d/*.cfg

auto eth0
iface eth0 inet static
address 172.31.36.46
netmask 255.255.240.0
broadcast 172.31.47.255
gateway 172.31.32.1
dns-nameserver 172.31.36.46
# dns-nameserver 172.31.0.2
# dns-nameserver 8.8.8.8
dns-search ad.company.com.my

/etc/hosts:

127.0.0.1 localhost localhost.localdomain
172.31.36.46        dc1.ad.company.com.my   dc1

# The following lines are desirable for IPv6 capable hosts
::1 ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts

/etc/resolv.conf

# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 172.31.36.46
search ad.company.com.my

/etc/hostname

dc1

/etc/krb5.conf

[libdefaults]
    default_realm = AD.COMPANY.COM.MY
    dns_lookup_realm = false
    dns_lookup_kdc = true

/etc/samba/smb.conf

[global]
    workgroup = AD
    realm = AD.COMPANY.COM.MY
    netbios name = DC1
    server role = active directory domain controller
    dns forwarder = 8.8.8.8
    idmap_ldb:use rfc2307 = yes

[netlogon]
    path = /var/lib/samba/sysvol/ad.company.com.my/scripts
    read only = No

[sysvol]
    path = /var/lib/samba/sysvol
    read only = No

Here is the output of the command: nslookup dc1.ad.company.com.my

Server:  ec2-ADDRESS.ap-southeast-1.compute.amazonaws.com
Address:  ADDRESS

Name:    dc1.ad.company.com.my
Address:  172.31.36.46

And then doing an SRV check:

C:\Users\user>nslookup
Default Server:  ec2-ADDRESS.ap-southeast-1.compute.amazonaws.com
Address:  ADDRESS

> set type=SRV
> _ldap._tcp.ad.company.com.my
Server:  ec2-ADDRESS.ap-southeast-1.compute.amazonaws.com
Address:  ADDRESS

_ldap._tcp.ad.company.com.my    SRV service location:
          priority       = 0
          weight         = 100
          port           = 389
          svr hostname   = dc1.ad.company.com.my

I've opened all traffic on the instance so that I know it's not a firewall issue.

So, what am I doing wrong?

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As a temporary solution add or update at windows 10 host HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Netlogon\Parameters\AllowSingleLabelDnsDomain to 1. Then reboot your windows 10 and try to add to domain with netbios name (in your case looks like you need to use AD)

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